include/linux/virtio_net.h

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _LINUX_VIRTIO_NET_H
   3 #define _LINUX_VIRTIO_NET_H
   4
   5 #include <linux/if_vlan.h>
   6 #include <linux/ip.h>
   7 #include <linux/ipv6.h>
   8 #include <linux/udp.h>
   9 #include <uapi/linux/tcp.h>
  10 #include <uapi/linux/virtio_net.h>
  11
  12 static inline bool virtio_net_hdr_match_proto(__be16 protocol, __u8 gso_type)
  13 {
  14         switch (gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
  15         case VIRTIO_NET_HDR_GSO_TCPV4:
  16                 return protocol == cpu_to_be16(ETH_P_IP);
  17         case VIRTIO_NET_HDR_GSO_TCPV6:
  18                 return protocol == cpu_to_be16(ETH_P_IPV6);
  19         case VIRTIO_NET_HDR_GSO_UDP:
  20         case VIRTIO_NET_HDR_GSO_UDP_L4:
  21                 return protocol == cpu_to_be16(ETH_P_IP) ||
  22                        protocol == cpu_to_be16(ETH_P_IPV6);
  23         default:
  24                 return false;
  25         }
  26 }
  27
  28 static inline int virtio_net_hdr_set_proto(struct sk_buff *skb,
  29                                            const struct virtio_net_hdr *hdr)
  30 {
  31         if (skb->protocol)
  32                 return 0;
  33
  34         switch (hdr->gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
  35         case VIRTIO_NET_HDR_GSO_TCPV4:
  36         case VIRTIO_NET_HDR_GSO_UDP:
  37         case VIRTIO_NET_HDR_GSO_UDP_L4:
  38                 skb->protocol = cpu_to_be16(ETH_P_IP);
  39                 break;
  40         case VIRTIO_NET_HDR_GSO_TCPV6:
  41                 skb->protocol = cpu_to_be16(ETH_P_IPV6);
  42                 break;
  43         default:
  44                 return -EINVAL;
  45         }
  46
  47         return 0;
  48 }
  49
  50 static inline int virtio_net_hdr_to_skb(struct sk_buff *skb,
  51                                         const struct virtio_net_hdr *hdr,
  52                                         bool little_endian)
  53 {
  54         unsigned int nh_min_len = sizeof(struct iphdr);
  55         unsigned int gso_type = 0;
  56         unsigned int thlen = 0;
  57         unsigned int p_off = 0;
  58         unsigned int ip_proto;
  59
  60         if (hdr->gso_type != VIRTIO_NET_HDR_GSO_NONE) {
  61                 switch (hdr->gso_type & ~VIRTIO_NET_HDR_GSO_ECN) {
  62                 case VIRTIO_NET_HDR_GSO_TCPV4:
  63                         gso_type = SKB_GSO_TCPV4;
  64                         ip_proto = IPPROTO_TCP;
  65                         thlen = sizeof(struct tcphdr);
  66                         break;
  67                 case VIRTIO_NET_HDR_GSO_TCPV6:
  68                         gso_type = SKB_GSO_TCPV6;
  69                         ip_proto = IPPROTO_TCP;
  70                         thlen = sizeof(struct tcphdr);
  71                         nh_min_len = sizeof(struct ipv6hdr);
  72                         break;
  73                 case VIRTIO_NET_HDR_GSO_UDP:
  74                         gso_type = SKB_GSO_UDP;
  75                         ip_proto = IPPROTO_UDP;
  76                         thlen = sizeof(struct udphdr);
  77                         break;
  78                 case VIRTIO_NET_HDR_GSO_UDP_L4:
  79                         gso_type = SKB_GSO_UDP_L4;
  80                         ip_proto = IPPROTO_UDP;
  81                         thlen = sizeof(struct udphdr);
  82                         break;
  83                 default:
  84                         return -EINVAL;
  85                 }
  86
  87                 if (hdr->gso_type & VIRTIO_NET_HDR_GSO_ECN)
  88                         gso_type |= SKB_GSO_TCP_ECN;
  89
  90                 if (hdr->gso_size == 0)
  91                         return -EINVAL;
  92         }
  93
  94         skb_reset_mac_header(skb);
  95
  96         if (hdr->flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) {
  97                 u32 start = __virtio16_to_cpu(little_endian, hdr->csum_start);
  98                 u32 off = __virtio16_to_cpu(little_endian, hdr->csum_offset);
  99                 u32 needed = start + max_t(u32, thlen, off + sizeof(__sum16));
 100
 101                 if (!pskb_may_pull(skb, needed))
 102                         return -EINVAL;
 103
 104                 if (!skb_partial_csum_set(skb, start, off))
 105                         return -EINVAL;
 106
 107                 nh_min_len = max_t(u32, nh_min_len, skb_transport_offset(skb));
 108                 p_off = nh_min_len + thlen;
 109                 if (!pskb_may_pull(skb, p_off))
 110                         return -EINVAL;
 111         } else {
 112                 /* gso packets without NEEDS_CSUM do not set transport_offset.
 113                  * probe and drop if does not match one of the above types.
 114                  */
 115                 if (gso_type && skb->network_header) {
 116                         struct flow_keys_basic keys;
 117
 118                         if (!skb->protocol) {
 119                                 __be16 protocol = dev_parse_header_protocol(skb);
 120
 121                                 if (!protocol)
 122                                         virtio_net_hdr_set_proto(skb, hdr);
 123                                 else if (!virtio_net_hdr_match_proto(protocol, hdr->gso_type))
 124                                         return -EINVAL;
 125                                 else
 126                                         skb->protocol = protocol;
 127                         }
 128 retry:
 129                         if (!skb_flow_dissect_flow_keys_basic(NULL, skb, &keys,
 130                                                               NULL, 0, 0, 0,
 131                                                               0)) {
 132                                 /* UFO does not specify ipv4 or 6: try both */
 133                                 if (gso_type & SKB_GSO_UDP &&
 134                                     skb->protocol == htons(ETH_P_IP)) {
 135                                         skb->protocol = htons(ETH_P_IPV6);
 136                                         goto retry;
 137                                 }
 138                                 return -EINVAL;
 139                         }
 140
 141                         p_off = keys.control.thoff + thlen;
 142                         if (!pskb_may_pull(skb, p_off) ||
 143                             keys.basic.ip_proto != ip_proto)
 144                                 return -EINVAL;
 145
 146                         skb_set_transport_header(skb, keys.control.thoff);
 147                 } else if (gso_type) {
 148                         p_off = nh_min_len + thlen;
 149                         if (!pskb_may_pull(skb, p_off))
 150                                 return -EINVAL;
 151                 }
 152         }
 153
 154         if (hdr->gso_type != VIRTIO_NET_HDR_GSO_NONE) {
 155                 u16 gso_size = __virtio16_to_cpu(little_endian, hdr->gso_size);
 156                 unsigned int nh_off = p_off;
 157                 struct skb_shared_info *shinfo = skb_shinfo(skb);
 158
 159                 switch (gso_type & ~SKB_GSO_TCP_ECN) {
 160                 case SKB_GSO_UDP:
 161                         /* UFO may not include transport header in gso_size. */
 162                         nh_off -= thlen;
 163                         break;
 164                 case SKB_GSO_UDP_L4:
 165                         if (!(hdr->flags & VIRTIO_NET_HDR_F_NEEDS_CSUM))
 166                                 return -EINVAL;
 167                         if (skb->csum_offset != offsetof(struct udphdr, check))
 168                                 return -EINVAL;
 169                         if (skb->len - p_off > gso_size * UDP_MAX_SEGMENTS)
 170                                 return -EINVAL;
 171                         if (gso_type != SKB_GSO_UDP_L4)
 172                                 return -EINVAL;
 173                         break;
 174                 }
 175
 176                 /* Kernel has a special handling for GSO_BY_FRAGS. */
 177                 if (gso_size == GSO_BY_FRAGS)
 178                         return -EINVAL;
 179
 180                 /* Too small packets are not really GSO ones. */
 181                 if (skb->len - nh_off > gso_size) {
 182                         shinfo->gso_size = gso_size;
 183                         shinfo->gso_type = gso_type;
 184
 185                         /* Header must be checked, and gso_segs computed. */
 186                         shinfo->gso_type |= SKB_GSO_DODGY;
 187                         shinfo->gso_segs = 0;
 188                 }
 189         }
 190
 191         return 0;
 192 }
 193
 194 static inline int virtio_net_hdr_from_skb(const struct sk_buff *skb,
 195                                           struct virtio_net_hdr *hdr,
 196                                           bool little_endian,
 197                                           bool has_data_valid,
 198                                           int vlan_hlen)
 199 {
 200         memset(hdr, 0, sizeof(*hdr));   /* no info leak */
 201
 202         if (skb_is_gso(skb)) {
 203                 struct skb_shared_info *sinfo = skb_shinfo(skb);
 204
 205                 /* This is a hint as to how much should be linear. */
 206                 hdr->hdr_len = __cpu_to_virtio16(little_endian,
 207                                                  skb_headlen(skb));
 208                 hdr->gso_size = __cpu_to_virtio16(little_endian,
 209                                                   sinfo->gso_size);
 210                 if (sinfo->gso_type & SKB_GSO_TCPV4)
 211                         hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV4;
 212                 else if (sinfo->gso_type & SKB_GSO_TCPV6)
 213                         hdr->gso_type = VIRTIO_NET_HDR_GSO_TCPV6;
 214                 else if (sinfo->gso_type & SKB_GSO_UDP_L4)
 215                         hdr->gso_type = VIRTIO_NET_HDR_GSO_UDP_L4;
 216                 else
 217                         return -EINVAL;
 218                 if (sinfo->gso_type & SKB_GSO_TCP_ECN)
 219                         hdr->gso_type |= VIRTIO_NET_HDR_GSO_ECN;
 220         } else
 221                 hdr->gso_type = VIRTIO_NET_HDR_GSO_NONE;
 222
 223         if (skb->ip_summed == CHECKSUM_PARTIAL) {
 224                 hdr->flags = VIRTIO_NET_HDR_F_NEEDS_CSUM;
 225                 hdr->csum_start = __cpu_to_virtio16(little_endian,
 226                         skb_checksum_start_offset(skb) + vlan_hlen);
 227                 hdr->csum_offset = __cpu_to_virtio16(little_endian,
 228                                 skb->csum_offset);
 229         } else if (has_data_valid &&
 230                    skb->ip_summed == CHECKSUM_UNNECESSARY) {
 231                 hdr->flags = VIRTIO_NET_HDR_F_DATA_VALID;
 232         } /* else everything is zero */
 233
 234         return 0;
 235 }
 236
 237 #endif /* _LINUX_VIRTIO_NET_H */